diff --git a/scripts/guibuild.py b/scripts/guibuild.py
index 85e1177..86d76a6 100755
--- a/scripts/guibuild.py
+++ b/scripts/guibuild.py
@@ -293,7 +293,7 @@ def fetch_dotnet() -> str:
         with zipfile.ZipFile(io.BytesIO(data)) as zf:
             zf.extractall(_DOTNET_STAGING)
     else:
-        with tarfile.open(io.BytesIO(data), "r:gz") as tf:
+        with tarfile.open(fileobj=io.BytesIO(data), mode="r:gz") as tf:
             tf.extractall(_DOTNET_STAGING)
     staged.chmod(staged.stat().st_mode | stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH)